Following completion of maintenance activities, the refinery’s 58,000-b/sd No. 2 crude unit was restarted and returned to service on Oct. 2, Norther Tier said.

The company, which took the unit down for unscheduled work on Sept. 17, did not disclose details regarding the nature or scope of the unplanned maintenance event.

In an Aug. 4 quarterly earnings call, Pres. and Chief Executive Officer David Lamp said Northern Tier originally intended to take the refinery’s No. 2 crude unit down for regularly scheduled maintenance in second-quarter 2016 during a planned turnaround. During that scheduled turnaround, the company also planned to execute modifications to the No. 2 crude unit and associated ultralow-sulfur diesel hydrotreater in order to boost crude throughput capacity and distillate yields, Lamp said.

Once completed, the crude unit and hydtrotreater revamp projects were to raise the refinery’s crude throughputs by up to 4,000 b/sd and diesel recovery by 2%, the company said in September.

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Future improvements

A separate project also remains under way at St. Paul Park to replace existing single-stage desalters with two-stage desalters at each of the refinery’s two crude units in order to increase crude-input flexibility at the site.

Designed to improve process reliability by reducing salt-related corrosion, the desalter replacements also are intended to equip the plant with greater flexibility to increase recovery of diesel vs. gasoline.

Northern Tier plans to complete installation of the desalter at the refinery’s 39,800-b/sd No. 1 crude unit by yearend, with No. 2 crude unit’s desalter scheduled to wrap installation by midyear 2016, the company said in early September.

Future projects to improve operations at St. Paul Park also under development include installation of a solvent deasphalting unit to fill available capacity in the refinery’s fluid catalytic cracking unit, as well as a revamp of plant’s No. 1 crude unit that would boost its processing capacity by a yet-to-be-disclosed volume.